New formula: boost-build

Boost.Jam is the engine of Boost.Build. The formula for Boost.Jam only
installs the engine leaving up to the user to manually install and
configure the remaining of Boost.Build. This revision adds Boost.Build
formula, but it conflicts with Boost.Jam if both are installed.

Closes Homebrew/homebrew#9133.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/boost-build.rb

@@ -0,0 +1,22 @@
+require 'formula'
+
+class BoostBuild < Formula
+  homepage 'http://boost.org/boost-build2/'
+  url 'http://downloads.sourceforge.net/project/boost/boost/1.48.0/boost_1_48_0.tar.bz2'
+  md5 'd1e9a7a7f532bb031a3c175d86688d95'
+  version '2011.04-svn'
+
+  head 'http://svn.boost.org/svn/boost/trunk/tools/build/v2/', :using => :svn
+
+  def install
+    if ARGV.build_head?
+      system "./bootstrap.sh"
+      system "./b2", "--prefix=#{prefix}", "install"
+    else
+      cd 'tools/build/v2' do
+        system "./bootstrap.sh"
+        system "./b2", "--prefix=#{prefix}", "install"
+      end
+    end
+  end
+end